serial: 8250: Integrate Fintek into 8250_base

The 8250_fintek driver advertises as the PNP0501 driver; however this
conflicts with the standard 16550A uart PNP0501. The conflict causes
the 8250_fintek driver to load with _every_ PNP0501, but never probe,
and causing the entire 8250 driver stack to unload if the 8250_fintek
driver is unloaded (modprobe doesn't know that 8250_pnp rather than
8250_fintek claimed the resource).

This patch merges the Fintek driver into 8250_base. On autoconfig_16550
the device is probed to verify if it is a FINTEK device or not.

This custom probing can be disabled completely via configuration. When a
Fintek device is not probed it will behave as a standard 16550A device,
with no RS485 capabilities.
Reported-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250.h

@@ -150,6 +150,12 @@ static inline int serial8250_pnp_init(void) { return 0; }
 static inline void serial8250_pnp_exit(void) { }
 #endif
 
+#ifdef CONFIG_SERIAL_8250_FINTEK
+int fintek_8250_probe(struct uart_8250_port *uart);
+#else
+static inline int fintek_8250_probe(struct uart_8250_port *uart) { return 0; }
+#endif
+
 #ifdef CONFIG_ARCH_OMAP1
 static inline int is_omap1_8250(struct uart_8250_port *pt)
 {

drivers/tty/serial/8250/8250_fintek.c

 /*
  *  Probe for F81216A LPC to 4 UART
  *
- *  Based on drivers/tty/serial/8250_pnp.c, by Russell King, et al
- *
- *  Copyright (C) 2014 Ricardo Ribalda, Qtechnology A/S
+ *  Copyright (C) 2014-2016 Ricardo Ribalda, Qtechnology A/S
  *
  *
  * This program is free software; you can redistribute it and/or modify
@@ -38,19 +36,15 @@
 #define RXW4C_IRA BIT(3)
 #define TXW4C_IRA BIT(2)
 
-#define DRIVER_NAME "8250_fintek"
-
 struct fintek_8250 {
 	u16 base_port;
 	u8 index;
 	u8 key;
-	long line;
 };
 
 static int fintek_8250_enter_key(u16 base_port, u8 key)
 {
-
-	if (!request_muxed_region(base_port, 2, DRIVER_NAME))
+	if (!request_muxed_region(base_port, 2, "8250_fintek"))
 		return -EBUSY;
 
 	outb(key, base_port + ADDR_PORT);
@@ -138,7 +132,7 @@ static int fintek_8250_rs485_config(struct uart_port *port,
 	return 0;
 }
 
-static int fintek_8250_base_port(u16 io_address, u8 *key, u8 *index)
+static int find_base_port(struct fintek_8250 *pdata, u16 io_address)
 {
 	static const u16 addr[] = {0x4e, 0x2e};
 	static const u8 keys[] = {0x77, 0xa0, 0x87, 0x67};
@@ -168,10 +162,13 @@ static int fintek_8250_base_port(u16 io_address, u8 *key, u8 *index)
 					continue;
 
 				fintek_8250_exit_key(addr[i]);
-				*key = keys[j];
-				*index = k;
-				return addr[i];
+				pdata->key = keys[j];
+				pdata->base_port = addr[i];
+				pdata->index = k;
+
+				return 0;
 			}
+
 			fintek_8250_exit_key(addr[i]);
 		}
 	}
@@ -179,104 +176,21 @@ static int fintek_8250_base_port(u16 io_address, u8 *key, u8 *index)
 	return -ENODEV;
 }
 
-static int
-fintek_8250_probe(struct pnp_dev *dev, const struct pnp_device_id *dev_id)
+int fintek_8250_probe(struct uart_8250_port *uart)
 {
-	struct uart_8250_port uart;
 	struct fintek_8250 *pdata;
-	int base_port;
-	u8 key;
-	u8 index;
-
-	if (!pnp_port_valid(dev, 0))
-		return -ENODEV;
+	struct fintek_8250 probe_data;
 
-	base_port = fintek_8250_base_port(pnp_port_start(dev, 0), &key, &index);
-	if (base_port < 0)
+	if (find_base_port(&probe_data, uart->port.iobase))
 		return -ENODEV;
 
-	memset(&uart, 0, sizeof(uart));
-
-	pdata = devm_kzalloc(&dev->dev, sizeof(*pdata), GFP_KERNEL);
+	pdata = devm_kzalloc(uart->port.dev, sizeof(*pdata), GFP_KERNEL);
 	if (!pdata)
 		return -ENOMEM;
-	uart.port.private_data = pdata;
 
-	if (!pnp_irq_valid(dev, 0))
-		return -ENODEV;
-	uart.port.irq = pnp_irq(dev, 0);
-	uart.port.iobase = pnp_port_start(dev, 0);
-	uart.port.iotype = UPIO_PORT;
-	uart.port.rs485_config = fintek_8250_rs485_config;
-
-	uart.port.flags |= UPF_SKIP_TEST | UPF_BOOT_AUTOCONF;
-	if (pnp_irq_flags(dev, 0) & IORESOURCE_IRQ_SHAREABLE)
-		uart.port.flags |= UPF_SHARE_IRQ;
-	uart.port.uartclk = 1843200;
-	uart.port.dev = &dev->dev;
-
-	pdata->key = key;
-	pdata->base_port = base_port;
-	pdata->index = index;
-	pdata->line = serial8250_register_8250_port(&uart);
-	if (pdata->line < 0)
-		return -ENODEV;
+	memcpy(pdata, &probe_data, sizeof(probe_data));
+	uart->port.rs485_config = fintek_8250_rs485_config;
+	uart->port.private_data = pdata;
 
-	pnp_set_drvdata(dev, pdata);
 	return 0;
 }
-
-static void fintek_8250_remove(struct pnp_dev *dev)
-{
-	struct fintek_8250 *pdata = pnp_get_drvdata(dev);
-
-	if (pdata)
-		serial8250_unregister_port(pdata->line);
-}
-
-#ifdef CONFIG_PM
-static int fintek_8250_suspend(struct pnp_dev *dev, pm_message_t state)
-{
-	struct fintek_8250 *pdata = pnp_get_drvdata(dev);
-
-	if (!pdata)
-		return -ENODEV;
-	serial8250_suspend_port(pdata->line);
-	return 0;
-}
-
-static int fintek_8250_resume(struct pnp_dev *dev)
-{
-	struct fintek_8250 *pdata = pnp_get_drvdata(dev);
-
-	if (!pdata)
-		return -ENODEV;
-	serial8250_resume_port(pdata->line);
-	return 0;
-}
-#else
-#define fintek_8250_suspend NULL
-#define fintek_8250_resume NULL
-#endif /* CONFIG_PM */
-
-static const struct pnp_device_id fintek_dev_table[] = {
-	/* Qtechnology Panel PC / IO1000 */
-	{ "PNP0501"},
-	{}
-};
-
-MODULE_DEVICE_TABLE(pnp, fintek_dev_table);
-
-static struct pnp_driver fintek_8250_driver = {
-	.name		= DRIVER_NAME,
-	.probe		= fintek_8250_probe,
-	.remove		= fintek_8250_remove,
-	.suspend	= fintek_8250_suspend,
-	.resume		= fintek_8250_resume,
-	.id_table	= fintek_dev_table,
-};
-
-module_pnp_driver(fintek_8250_driver);
-MODULE_DESCRIPTION("Fintek F812164 module");
-MODULE_AUTHOR("Ricardo Ribalda <ricardo.ribalda@gmail.com>");
-MODULE_LICENSE("GPL");

drivers/tty/serial/8250/8250_port.c

@@ -1315,6 +1315,13 @@ static void autoconfig(struct uart_8250_port *up)
 
 out_lock:
 	spin_unlock_irqrestore(&port->lock, flags);
+
+	/*
+	 * Check if the device is a Fintek F81216A
+	 */
+	if (port->type == PORT_16550A)
+		fintek_8250_probe(up);
+
 	if (up->capabilities != old_capabilities) {
 		pr_warn("ttyS%d: detected caps %08x should be %08x\n",
 		       serial_index(port), old_capabilities,

drivers/tty/serial/8250/Kconfig

@@ -57,6 +57,18 @@ config SERIAL_8250_PNP
 	  This builds standard PNP serial support. You may be able to
 	  disable this feature if you only need legacy serial support.
 
+config SERIAL_8250_FINTEK
+	bool "Support for Fintek F81216A LPC to 4 UART RS485 API"
+	depends on SERIAL_8250
+	---help---
+	  Selecting this option will add support for the RS485 capabilities
+	  of the Fintek F81216A LPC to 4 UART.
+
+	  If this option is not selected the device will be configured as a
+	  standard 16550A serial port.
+
+	  If unsure, say N.
+
 config SERIAL_8250_CONSOLE
 	bool "Console on 8250/16550 and compatible serial port"
 	depends on SERIAL_8250=y
@@ -358,14 +370,6 @@ config SERIAL_8250_OMAP_TTYO_FIXUP
 	  not booting kernel because the serial console remains silent in case
 	  they forgot to update the command line.
 
-config SERIAL_8250_FINTEK
-	tristate "Support for Fintek F81216A LPC to 4 UART"
-	depends on SERIAL_8250 && PNP
-	help
-	  Selecting this option will add support for the Fintek F81216A
-	  LPC to 4 UART. This device has some RS485 functionality not available
-	  through the PNP driver. If unsure, say N.
-
 config SERIAL_8250_LPC18XX
 	tristate "NXP LPC18xx/43xx serial port support"
 	depends on SERIAL_8250 && OF && (ARCH_LPC18XX || COMPILE_TEST)

drivers/tty/serial/8250/Makefile

@@ -7,6 +7,7 @@ obj-$(CONFIG_SERIAL_8250)		+= 8250.o 8250_base.o
 8250-$(CONFIG_SERIAL_8250_PNP)		+= 8250_pnp.o
 8250_base-y				:= 8250_port.o
 8250_base-$(CONFIG_SERIAL_8250_DMA)	+= 8250_dma.o
+8250_base-$(CONFIG_SERIAL_8250_FINTEK)	+= 8250_fintek.o
 obj-$(CONFIG_SERIAL_8250_GSC)		+= 8250_gsc.o
 obj-$(CONFIG_SERIAL_8250_PCI)		+= 8250_pci.o
 obj-$(CONFIG_SERIAL_8250_HP300)		+= 8250_hp300.o
@@ -23,7 +24,6 @@ obj-$(CONFIG_SERIAL_8250_FSL)		+= 8250_fsl.o
 obj-$(CONFIG_SERIAL_8250_DW)		+= 8250_dw.o
 obj-$(CONFIG_SERIAL_8250_EM)		+= 8250_em.o
 obj-$(CONFIG_SERIAL_8250_OMAP)		+= 8250_omap.o
-obj-$(CONFIG_SERIAL_8250_FINTEK)	+= 8250_fintek.o
 obj-$(CONFIG_SERIAL_8250_LPC18XX)	+= 8250_lpc18xx.o
 obj-$(CONFIG_SERIAL_8250_MT6577)	+= 8250_mtk.o
 obj-$(CONFIG_SERIAL_8250_UNIPHIER)	+= 8250_uniphier.o